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Dimethyl and diethyl acetylenedicarboxylate react smoothly with naphthols, such as methyl 1-hydroxynaphthalene-2-carboxylate and methyl 2-hydroxynaphthalene-1-carboxylate, in the presence of triphenylphosphine to produce highly functionalized benzochromenes (coumarins) in high yields via intramolecular Wittig reaction on the ylide intermediate. The 1H and 13C NMR data of these compounds are compared...